The relative roles of hormones and psychosocial factors on sex specific behaviors have been explored in both animals and humans. Recently, considerable attention has focused on differences between the sexes In cognitive abilities, such as spatial versus verbal information processing. These abilities have been purported to be related to the lateralized functional organization of the cerebral hemispheres. From these studies and from clinical neuropsychological studies it has been suggested that male and female brains are organized differently. Prenatal and postnatal exposure to sex hormones are believed to play a significant role in these neurocognitive differences between the sexes. The proposed investigation, will explore the potential relationship between early sex hormone exposure and neurocognitive functioning. The present proposal has two major purposes: The first Is to study the possible role of prenatal/prepubertal sex hormones on cognitive abilities and electrophysiological Indices of cerebral functional organization. This goal will be accomplished through the study of Turner Syndrome US) and normal pre pubertal female and male subjects. The TS and normal female and male subjects provide differing prenatal sex hormone exposed groups. TS females typically lack normal exposure to prenatal sex hormones, whereas normal females and males are exposed to different levels of prenatal estrogens and androgens. By studying these groups with different prenatal exposure to hormones, theoretical questions can be addressed pertaining to the role of these hormones on brain organization and on the development of cognition in the human. The second major purpose Is to develop a neurobehavioral profile of TS individuals, to examine Individual differences in cognitive, neurophysiological and psychosocial variables and to relate ability to process social affective information to psychosocial variables, such as self concept and behavioral adjustment. This work should provide a better understanding of the potential role of prenatal hormones In neurocognitive functioning as well as a much more complete understanding of the relationship between genotype and neurocognitive factors In TS women. Such information could, serve as a basis for early detection of strengths and weaknesses in TS women and thereby lead to improved educational approaches In this population as well as in other children with learning difficulties.